Ambulances and buses evacuating people drive out of a rebel-held part of Aleppo, Syria December 15, 2016. REUTERS/Omar Sanadiki

BEIRUT (Reuters) - Dozens of buses carrying evacuees from the last rebel-held district of Aleppo travelled to the insurgent-held areas of countryside outside the city early on Monday, a United Nations official and a war monitor said.

The U.N. official said 50 buses and two ambulances had left the rebel zone, while the Britain-based Syrian Observatory for Human Rights said that 65 buses had left carrying about 3,500 people.